(a) Field of the Invention
The present invention relates to a liquid crystal display.
(b) Description of the Related Art
A liquid crystal display (LCD) is one of the most widely used types of flat panel displays. A liquid crystal display includes two display panels with field generating electrodes, such as pixel electrodes and a common electrode. A liquid crystal layer is positioned between the two display panels. Voltages are applied to the field generating electrodes to generate electric fields in the liquid crystal layer and thus to control the orientation of the liquid crystal molecules in the liquid crystal layer, and hence the polarization of incident light, as needed to display a desired image.
The liquid crystal display includes switching elements connected to pixel electrodes and also includes signal lines such as data lines and gate lines for applying voltages to the pixel electrodes via the switching elements.
A popular LCD type is a vertical alignment (VA) mode LCD, in which the longitudinal axes of the liquid crystal molecules are perpendicular to the upper and lower display panels when no electric field is applied. In this LCD type, a high contrast ratio and a large reference viewing angle can be easily implemented. The reference viewing angle can be defined as a viewing angle at which the contrast ratio is 1:10, or a viewing angle at which luminance inversion occurs at some predefined luminance level.
A very-large aperture ratio structure having wide pixel electrodes in order to improve the aperture ratio of a liquid crystal display has been suggested. In such a structure, the pixel electrodes and the data lines overlap with each other, increasing the parasitic capacitance. If there is a semiconductor layer present under the data lines, parasitic capacitance is also obtained between the semiconductor layer and the pixel electrodes, thereby affecting pixel electrode voltages.
It is desirable to improve the aperture ratio of a liquid crystal display and reduce the effect of the semiconductor layer on pixel electrode voltages.